One event that happened almost two decades ago is the lynch pin for your argument (vis, solid rockets are not safe enough for man-rated hardware). They haven't been an issue for over fifteen years. You have one launch to support your claim, while I have on my side a significant number of launches of the much despised shuttle since the launch you cite. The SRBs are not a concern for current return to flight activities.

Who's yelling?

DKH

P.S. The parachute failed during reentry of Soyuz 1. Do you think this data is enough to say that parachutes are dangerously unreliable for use as part of a man-rated reentry mechanism.

No one's yelling, our forum just has a dry sense of humor reeking with sarcasm I think a little of that might come from being intelligent, every genius I've met has an amazingly dry sense of humor, so I suppose its not a BAD thing... (I've met my share... one of them being my Calculus and AP statistics teacher, who was on the team that created element 110... Dr. J. Rigol, you can look him up...)

And yes, I'm a senior... however no groveling is required, as entertaining as it might be... I stopped being elitist after 8th grade because when I got to high school, most of my friends were much older than I was and treated me as an equal, so I decided to pay it forward (good movie by the way ).

Clearly propulsion systems are the largest cause of mission failures on orbital launch vehicles. Using the data only as Futron interprets it, one might be led to the conclusion that solids are only marginally less safe than liquid engines are on all launch vehicles. However, that would be a bit of an obtuse extrapolation if applied to suborbital space tourism vehicles as it's easier to have a successful mission. As long as everyone who rode the rocket is still alive at the end of the day, you have a successful mission. The funny thing about solid rockets is that they either fail catastrophically and take the whole ship down with them or work just fine. On the other hand, many of the liquid engine failures described in the Futron report would have been easily survivable and did not damage any component of the vehicle other than the engine. However, an expendable launch vehicle must send its payload into a perfect or near-perfect orbit to have a successful mission. If it has an engine failure, that's it. Not so for space tourism.

The reason for this is that, while a liquid rocket engine runs in a very similar manner to a gas turbine engine, in which fuel and oxidizer are stored seperately, mixed in a combustion chamber, and then burned, a solid rocket's fuel and oxidizer are pre-mixed an cast into the rocket's casing. Once the reaction is started in a solid engine, it can't be shut down or controlled beyond what was re-cast into the motor. If the engine starts to burn through its casing, as happened to Challenger, too bad so sad. There's nothing anyone can do to stop a solid rocket once it's been started, that makes it completely unacceptably unsafe for use in manned vehicles.

Additionally, solid rockets are just not very easy to reuse. While a liquid rocket can be inspected and fueled up to reuse, practically a gas-n-go operation ideally, solids are tricky to use again. They have to be cleaned out, prepared for casting, carefully recast, and rigged up for launch again. By the time you're done, you practically have a new engine. Solids don't scale well, either. Because the fuel tank and engine are one and the same, they have to be assembled at the same time and transported together. When you get above a certain size there's just no way to do that anymore and the motor has to be broken down into smaller components hooked up with o-rings. That adds numerous headaches to the design and reuse process and also opens the door for o-ring burn throughs (once again, back to the Challenger). As if that weren't enough, solid rockets that use ammonium perchlorate (the typical blend of fuel) are horridly toxic and all are dangerous to handle on the ground. One spark or bump in the wrong place and the whole thing could explode.

Your Soyuz 1 analogy was interesting, but a little bit flawed. I think that there are enough data from aircraft vs parachute operations to suggest that horizontal landing a la the Space Shuttle is safer than parachute landing. However, there is nothing fundamentally unsound about the concept of parachute landing, and the only obstacles potentially witholding parachutes from use in space tourism is the inconvienance they entail and their relatively unfavorable safety record compared to other landing systems. There are, however, many insurmountable problems with the use of solid rocket engines in space tourism vehicles, as I described in hopefully enough detail for a layman above.

If we can't see eye to eye, at least maybe we can understand each other's points now.

_________________"Yes, that series of words I just said made perfect sense!"
-Professor Hubert Farnsworth

Ok, so now we're moving away from human space flight altogether. Even then the data differences are ultimately quite small (broadly put it's 6 vs 7 incidents) and I see no discussion in the futron report which concerns the question that any of the failures discussed are survivable at all (the report concerns unmanned US rockets launched since 1984). So the issue of survivability is something you are making assumptions about (please include your reasoning). Plus you missed the point of the soyuz 1 argument altogether (it was supposed to highlight the old chestnut about exceptions proving the rule). So there isn't too much point in continuing here.

I raised the point that a large number of US human passenger flights carried out safely (with a single exception relating to the question at hand) over almost the last thirty years, in which solid rockets had been used, demonstrably shows that solid rockets are considered by a significant number of actual rocket scientists to be safe enough to be a part of man-rated flight hardware. In the end the actual saftey issues which come up between using one or the other form of propulsion are much smaller, in terms of space-tourism for example, than the issues associated with re-entry.

Sorry braunster, you're handwaving cuts no ice. We will have to disagree on this because you refuse to recognise the difference between your (strident) opinion and decades of existing actual data where the form of propulsion we are discussing did not fail.

Where exactly does one draw the line between arm-waving and legitimate counter-cultural arguments? I always assumed that if someone comes out making a buch of wild, looney points and then spends the rest of the time insulting anyone who disagrees with them (or calling them racists in BRNA's case) while making no acutal supporting arguments then that's arm-waving. By contrast, when someone comes out making some seemingly wild, looney points and then backs them up with pre-meditated evidence then that's legitimate debate. It's one of those things you have to interpret for yourself, but I did back up the points that I made.

I suppose that the Challenger argument was relatively weak, but saying that just because tons of rocket scientists think something's safe it automatically is safe is a weak argument as well. The cameras on the pad and the fuel tank clearly picked up a large chunk of foam broadsiding Columbia's heat shield when it launched on January 16. This information was reviewed for over two weeks before Columbia attempted reentry, and NASA's scientists unanimously agreed that the foam could not have possibly damaged the heat sheild enough for it to be of concern. We all know how that turned out; this is just a cautionary tale that sometimes hundreds of people with PhDs and years of experience in rocket science can in fact be totally bass-ackwards in their thinking and be completely absolutely wrong. Granted, only one shuttle has disentigrated on reentry, but there are undoubtedly numerous cases of many rocket scientists being wrong. Just because the bandwagon argument looks so good on paper doesn't make it true.

Even if you disregard the Challenger incident, the other evidence that I pushed forward still stands. Are we all agreed that any engine failure of a solid rocket will be utterly disastorous for a mission? The sticky point is which liquid engine failures would have been catastrophic as well.

As it stands in the begining of Futron report, there is a ratio of 6:7 liquid to solid rocket engine catastrophic failures. However, towards the bottom of the document it mentions more specific information on what happened in each failure. On the first failure, a Titan 34D, the propellant feed system of one of the rocket's main engines failed, let's assume that that was a catastrophic failue. Another Titan 34D's propellant line ruptured, so let's group that in the same category. However, on the next three failures the main engines on two Atlas 1's failed to produce full power and one Centaur engine did not come online. That's hardly a universally catastrophic failue, and while it would result in an aborted mission, a space tourism vehicle could either glide or parachute to a landing or activate an escape tower if the engine throttled down unintentionally. As for the Centaur engine failure, assuming enough redundancy was built into the design, disaster could be averted even in the event of an engine failure. That kind of redundancy is built into rockets like the Falcon V and the Saturn V, so it shouldn't be too hard to replicate. The final liquid engine failure, a Delta 3 main engine's combustion chamber rupture, would probably have been catastrophic.

So in review at least three of the liquid engine failures would have been catastrophic, but another three could have been mitigated by improved system safety. This brings the ratio of liquid/solid engine failures down to 3:7. According to Futron's data, liquids are twice as safe in space tourism applications than solids are. For more information on solid rocket motors, and what applications they are ideal for, Astronautix is a very good resource:
http://astronautix.com/props/solid.htm

The whole argument about solid rocket safety kinda misses the point I was trying to make. I was stating my concerns that STC is not up to the task of developing private space tourism vehicles, and with the announcement that they will be in "hibernation" for the near future at least appears to confirm my fears. We have all been too optimistic. This was the real point I was trying to make. Sorry for being a killjoy, but the points I made remain legitimate.

_________________"Yes, that series of words I just said made perfect sense!"
-Professor Hubert Farnsworth

DKH, I'd say that was decently sound support for his assertions. Hmm, so all the data is on your side, and only assumptions and opinion is against your data? That sounds a bit too preposterous of a claim, even for you. Speaking of strident,... Anyway, so solids frequently do provide an attractive and successful option for propulsion. The point, though, is one of minimizing risks. While NASA has been known for many useful innovations and contributions to society (just see their website to see that horn sounded), I think the recent trend towards private sector involvement is largely with the motivation of getting more 'out-of-the-box' thinking (for low cost, yes...). Just because NASA scientists haven't made a major paradigm shift that would require re-engineering, the majority of the shuttle propulsion systems and considerable man-hour investment doesn't necessarily mean that the current mode of operation is the best.

Good motivation in trying to maintain a standard of credibility in others' posts - it would just be nice to see some risk on your party in contributing something (that ... yikes ... may be criticised itself)

Braunster (sorry, I think that nick may stick), why are you letting DKH make you do all the work? I saw very little in the way of sources or supporting factual data from him. Your sources were unfortunately tertiary (primary or secondary may have provided a bit more in the way of detail and credibility regarding the debated 'catastrophic' nature.

Finally, DKH, perhaps you should be careful of the context within which you wish "good luck" with b'ster's studies. I'd have to say that I'm fairly impressed with the contributions that many of the High School students have provided, and such an attempt to establish a credibility gradient between the two of you is rather low.

What killed STC is not the technology, but the lack of funding. You can argue all day long about how their technology was flawed (and perhaps that this was what scared off investors), but they faced a perhaps more difficult task in lining up investors.

Thus far, only one team seems to have been successful at getting unconnected large investors to pony up, and that's been Scaled. Carmack, Musk, etc. are all wealthy self-funders. (Note - I'm not talking about a couple hundred k$ from Golden Palace, or $50k from a space society - I'm talking the multiple of millions of dollars to develop a real space tourism program.)

That's why my hat is off to the boys from forks from a technological standpoint - in my mind they went father with less than any other team. They also really put their butts on the line, quitting their day jobs, getting friends and family to contribute savings, etc.

In the space tourism business, sometimes just surviving is an accomplishment onto itself.

The interesting thing is that if we believe the marketing surveys, there's real money to be made with space tourism. We all know who the #1 player is likely going to be (Virgin/Scaled), but there's still good cash to be made as a #2 with 10-15% of the market. Any bets on who that will be?

This is so weird. I can't even wish anyone good luck without someone else reading some sort of evil-minded sub-text into it. But back on topic ...

Ok, let's look at a few statements made by SVB in this thread ...

Quote:

the fundamental matter is that solid rocket motors are not safe enough for manned spaceflight.

So I brought up the ongoing shuttle program. To which SVB makes the reply ...

Quote:

this is just a cautionary tale that sometimes hundreds of people with PhDs and years of experience in rocket science can in fact be totally bass-ackwards in their thinking and be completely absolutely wrong.

So my example includes the experience of one of only two regular manned flight programs in existence. The shuttle program has had two spectacular failures. One of which involved SRBs and one which did not. SRBs have, for nearly two decades, not been considered an issue by the people who actually employ them to carry out manned space flight.

The cautionary tale (SVB please take note) is that sometimes "stuff" happens. Which is pretty much the same thing as what you said. If you play with increasingly complex systems you accordingly raise the risk that something goes wrong. With a long enough time line every system's chance of failure rises to 100%. But the "stuff" that happened to color your principal thought on the issue at hand (man-rated flight hardware using solid rockets) has happened exactly once. There's the hard data point I have already used myself, which was missed by slycker.

Now I really liked the data that SVB did come up with. It was strong but it was not for manned space programs. For unmanned launches there is an appreciation that failure rates are accepted and even accounted for (insurance) where they are not in manned programs. Accordingly the engineering is geared only to meet those requirements. This is not building to fail, but rather building within economic constraints and acceptable risk analyses. Risk analyses which are quite different from those made in the context of manned flight.

Also, while the figures were nicely put it is slightly disingenuous to refer to a 6:7 or 3:7 ratio when there are only 6 versus 7 (or 3 versus 7) events being talked about. Ratios are meant to express deconstructions of large number comparisons. This doesn't mean SVB is wrong, it's just that he's putting at least as much spin on things as when I point to the NASA record as my example (for which I don't provide numbers because the concept I raise is pretty darn obvious slycker). My arguments against these specific figures are two-fold, the numbers are too small and therefore still too close to make the blanket call "solid rockets bad, liquid good" and secondly, these particular units were not engineered with human space-flight in mind, thus higher fail rates are acceptable and taken into account for.

Part of this thread boils down to the following ... it is possible that SVB doesn't think that NASA knows what it is doing. Therefor there is some sort of enormous conspiracy at work which is funnelling billions of public dollars into a deeply flawed program. If a bright high school student knows this then how come it's still happening?

Why hasn't NASA been shut down? They have killed many people. Is it because they have been making terrible errors in judgement or is it because during a long and difficult development program "stuff", from time to time, has happened.

If it's the latter then the question cycles back to ask if SVB's original statement "that solid rockets are not safe enough for man-rated flight systems" is true or not. In my opinion, this is not a true statement. The true statement (according to my opinion which is based on the experience of "hundreds of PhDs" and the fact that no matter what "stuff" happens) is this ... mostly, yes they are safe enough.

I wish luck to all high school students in your various pursuits. Whether that's good or bad I leave it up to your interpretation.

Where exactly does one draw the line between arm-waving and legitimate counter-cultural arguments? I always assumed that if someone comes out making a buch of wild, looney points and then spends the rest of the time insulting anyone who disagrees with them (or calling them racists in BRNA's case) while making no acutal supporting arguments then that's arm-waving. By contrast, when someone comes out making some seemingly wild, looney points and then backs them up with pre-meditated evidence then that's legitimate debate. It's one of those things you have to interpret for yourself, but I did back up the points that I made.

Oh man give it a break. Point out the insults please. Point out the wild looney points too. All I did was say that a bunch of people having done something for a long time must know what they are doing now. Is that a wild and looney point?

In this thread I've been the mild man of borneo. It's you, braunster, who's been the shrieking sheik.

Dont they use solid rockets for most Launch Escape Systems? If they were that unreliable then wouldn't they use something else?

Also the US Airforce used small strap on solid rockets to enable planes to take off in shorter distances. These would all count as manned rocket flights.

I must admit given all the above, while I have no problem using solids for additional thrust, I am not sure that I would rely on them soley. I have seen a design using a single shuttle solid booster to launch a small manned craft on the ATK site so they obviously think it would be OK to use them (sorry I've looked for the article but cant find it again, I think they have redesigned their site since I was there last).

_________________A journey of a thousand miles begins with a single step.

DKH,
I couldn't resist. In context, that comment seemed a bit too convenient. Anyway... It seemed that SVB needed some of your criticisms concretely spelled out. I didn't say that you didn't have any factual data support, only little - and it didn't hurt to see some heat turned your way as well

- with regards to the authority of NASA PhD's - I do not intend at all to detract from the sheer brilliance of the many minds that work there - I just have this nasty knee-jerk reaction to an appeal to an authority.

- I do believe, however, that it is precisely the difference in manned vs. non-manned flight that spurred this discourse on the potential risks of solid propellants. There is, of course, very limited appropriate data to draw upon for speculation regarding safety.
For myself, while safety is of cursory concern, my main concern is how they do not provide variable thrust and so are limited to a 'booster' role, to provide raw thrust and achieve escape velocity (yes, very necessary, yet limited in any more complicated missions).

I also wish aspiring students the best of luck, as I realize that their hard studies are probably the only way I will ever get to the moon (okay, orbital or at least sub-orbital) in my lifetime.

Part of this thread boils down to the following ... it is possible that SVB doesn't think that NASA knows what it is doing. Therefor there is some sort of enormous conspiracy at work which is funnelling billions of public dollars into a deeply flawed program. If a bright high school student knows this then how come it's still happening?

I never meant to imply that NASA is a conspiracy that shunts money into knowinlgy flawed programs. What I meant to say was that NASA has had a deeply flawed safety culture ever since it became complacent with the space shuttle. The day before Challenger was launched for the last time there were vehement arguments between engineers and management in NASA over whether or not the shuttle should be launched in such cold weather. In the end it boiled down to the managers not caring enough about safety and having enough power to disregard the engineers; that is a flawed safety culture. Columbia was a different matter and perhaps it's easier to forgive NASA in that case, but they really should have thought that maybe the foam could come off the main tank and maybe strike the shuttle's heat shield at high speed, and they should have run some tests on the matter just to make sure that it was a safe system. The shuttle's SRBs are a mediocre solution to solving the problem of getting the orbiter up, as many NASA engineers have previously stated.

Why don't we drop the subject of who we are outside the internet? Does the fact that I am a high school student have absolutely any bearing whatsoever in this issue one way or the other? It's a bit of a moot point.

Quote:

Senior Von Braun wrote: Where exactly does one draw the line between arm-waving and legitimate counter-cultural arguments? I always assumed that if someone comes out making a buch of wild, looney points and then spends the rest of the time insulting anyone who disagrees with them (or calling them racists in BRNA's case) while making no acutal supporting arguments then that's arm-waving. By contrast, when someone comes out making some seemingly wild, looney points and then backs them up with pre-meditated evidence then that's legitimate debate. It's one of those things you have to interpret for yourself, but I did back up the points that I made.

Oh man give it a break. Point out the insults please. Point out the wild looney points too. All I did was say that a bunch of people having done something for a long time must know what they are doing now. Is that a wild and looney point?

In this thread I've been the mild man of borneo. It's you, braunster, who's been the shrieking sheik.

First off, I believe it was you who asserted that no one was yelling. Secondly, you've misinterpreted what I said. I was trying to say that I had backed up my points with real arguments and wasn't just out arm-waving, as you accused me of doing. No one's accusing you of anything, Mr. Mild Man of Borneo.

Using solid rockets in escape towers is a little different from using them as the primary propulsion sytem. For one thing, the solids used in escape towers and RATO systems are a lot smaller than those used as main engines and are thus are vastly easier and safer to transport and ground handle. Liquid rockets can't really be used for escape systems because the need a second or two to ignite and rev up to full throttle. By contrast, solids are primed and ready to go at a hundredth of a second's notice as soon as the fuel is cast, making them ideal for applications in which you could be dead in a second if it takes that long for the rocket to turn on. I could also point out that esacpe towers are smaller than main engines and only burn for seconds rather than minutes, making a catastrophic failure much less likely.

In any case, the primary commentary that I wanted to get across wasn't about solids, it was about optimism. The alt. space community just has had too much of it ever since Scaled took home the X Prize and I think that we (alt. spacers) all need to get our feet back on the ground and realize that the future isn't quite as rosy as it might seem to be. Just a thought, for what it's worth.

_________________"Yes, that series of words I just said made perfect sense!"
-Professor Hubert Farnsworth

I guess I interpreted your phrase "the fundamental matter is that solid rocket motors are not safe enough for manned spaceflight" as being the explanation in condensation as to why you think STC shouldn't have been supported/allowed.

That's why I pointed out that NASA continues to use them for manned spaceflight and this seems to put a hole in your argument.

Was I incorrect in this interpretation?

DKH

P.S. I brought up the highschool student thing as a contrast to your "hundreds of PhDs" thing. I'm not picking on you because you're in highschool. I think it's cool that a highschool student has the chutzpah to keep up this toasting, keep keeping it up.

P.P.S. I work in dermatology, so I can safely recommend (with more authority on the matter than you can imagine) that you grow a thicker skin. Life will be a happier experience.

I guess I interpreted your phrase "the fundamental matter is that solid rocket motors are not safe enough for manned spaceflight" as being the explanation in condensation as to why you think STC shouldn't have been supported/allowed.

That's why I pointed out that NASA continues to use them for manned spaceflight and this seems to put a hole in your argument.

Was I incorrect in this interpretation?

No, not incorrect, just incomplete. For one thing I didn't mean to say that STC should never have been supported. I meant to say that we should all take prospective alt. space companies like STC with a pretty hefty grain of salt. This sense of skepticism is overlooked very often, and the lack of it in the alt. space community is a big part of the giggle factor. It's hard for outsiders to take a group like the members of these forums seriously when they expect every team to deliver what they claim to be capible of. STC should be supported, yes, but one should think twice before taking them seriously.

There is, actually, a method to my madness and hopefully I can demistify some of it for you. Since the private commercial space travel industry is still in its infancy it is very difficult for any company entering the field to find investment and support, and I believe that the alt. space community (eg xprizenews.org forum members) should offer whatever token of support it has to any team gutsy enough to enter the arena, provided it can show at least a certain amount of initial credibility. However, one should also take into consideration that any company entering the field has a very low likelihood of sucess. In short, we should hope for the best (something pretty much everyone here has nailed) but expect the worst (much rarer). STC never had much of a shot at putting Rubicon into space, the solid rocket inconveniances were just a small part of their plight.

I should also add that the shuttle is a little different than a commercial space tourism vehicle. Despite all of the NASA party lines that it makes orbital flight "routine," the shuttle is very much a cutting-edge (less so as it ages) experimental test vehicle. The shuttle's failure rate would be completely unacceptable for commercial space flight. The only reason it keeps on flying is because deep down all of the program managers know it is still experimental and therefore will have a relatively high failure rate. A successful space tourism vehicle will have to be far safer than NASA has allowed the shuttle to be.

P.S. My skin's just fine with its current thickness. I haven't been getting angry, sorry if it seems like that. Well, I guess it's time to go chill out in the spaceflight cafe...

_________________"Yes, that series of words I just said made perfect sense!"
-Professor Hubert Farnsworth

Dr. Keith and Senor von Braun owe each other a debt of gratitude for mutual intellectual stimulation... it is an awesome thing to watch and read.. and I mean this as a compliment to both.... I'm learning things and being inspired to reconsider previously held opinions.